The Molecular Biology Core will be used by subprojects 1, 2, 4, and 6. The core will provide services that will greatly facilitate the research proposed by subprojects 1 and 6, and more importantly, the core will allow subprojects 2 and 4 access to methodologies absent from there own laboratories. Access to such a core is essential because implementation of these technologies in each investigators' laboratory would be prohibitively expensive. For example, Dr. Coronado (subproject 2) wishes to obtain a reliable and abundant supply of certain toxins, from the Mexican breaded lizard Heloderma horridum horridum, that will be used as tools to dissect the function of the ryanodine receptor in cardiac muscle. Services provided by the Molecular Biology Core will include isolating the toxin cDNAs, determining the DNA sequence and constructing expression vectors that will permit the production of the toxins in bacteria. The expression and purification of these recombinant toxins will be done by the Protein Biochemistry Core (Core B). Dr. Coronado does not have either the equipment or the expertise to allow this to be done in his own laboratory. However, the use of the two core services will enable this project to be completed in a timely manner.